The layout of the terminal doesn't help. Without a new complete new build, they're still having to tack wee bits on here and there. That 1977 structure is still the basis of everything there today and it was not designed for anything close to what it's serving now. BAA building a whole new pier on the cheap with no airbridge access or UK Border facility was a complete farce.
The owners, GIP try and build up a business before selling it on at profit, they're investors rather than operators in the traditional sense but they've worked wonders at Gatwick in terms of infrastrucutre whereas at EDI, they FUBARed the new security hall. Quite the least intuitive piece of design I have seen in a major UK airport, clearly senior management took their eye off the ball, or they have a great new business team and a poor operational support structure.